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//! This crate provides a client for interacting with [Apache
//! ZooKeeper](https://zookeeper.apache.org/), a highly reliable distributed service for
//! maintaining configuration information, naming, providing distributed synchronization, and
//! providing group services.
//!
//! # About ZooKeeper
//!
//! The [ZooKeeper Overview](https://zookeeper.apache.org/doc/current/zookeeperOver.html) provides
//! a thorough introduction to ZooKeeper, but we'll repeat the most important points here. At its
//! [heart](https://zookeeper.apache.org/doc/current/zookeeperOver.html#sc_designGoals), ZooKeeper
//! is a [hierarchical key-value
//! store](https://zookeeper.apache.org/doc/current/zookeeperOver.html#sc_dataModelNameSpace) (that
//! is, keys can have "sub-keys"), which additional mechanisms that guarantee consistent operation
//! across client and server failures. Keys in ZooKeeper look like paths (e.g., `/key/subkey`), and
//! every item along a path is called a
//! "[Znode](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_zkDataModel_znodes)".
//! Each Znode (including those with children) can also have associated data, which can be queried
//! and updated like in other key-value stores. Along with its data and children, each Znode stores
//! meta-information such as [access-control
//! lists](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_ZooKeeperAccessControl),
//! [modification
//! timestamps](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_timeInZk),
//! and a version number
//! that allows clients to avoid stepping on each other's toes when accessing values (more on that
//! later).
//!
//! ## Operations
//!
//! ZooKeeper's API consists of the same basic operations you would expect to find in a
//! file-system: [`create`](struct.ZooKeeper.html#method.create) for creating new Znodes,
//! [`delete`](struct.ZooKeeper.html#method.delete) for removing them,
//! [`exists`](struct.ZooKeeper.html#method.exists) for checking if a node exists,
//! [`get_data`](struct.ZooKeeper.html#method.get_data) and
//! [`set_data`](struct.ZooKeeper.html#method.set_data) for getting and setting a node's associated
//! data respectively, and [`get_children`](struct.ZooKeeper.html#method.get_children) for
//! retrieving the children of a given node (i.e., its subkeys). For all of these operations,
//! ZooKeeper gives [strong
//! guarantees](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#ch_zkGuarantees)
//! about what happens when there are multiple clients interacting with the system, or even what
//! happens in response to system and network failures.
//!
//! ## Ephemeral nodes
//!
//! When you create a Znode, you also specify a [`CreateMode`]. Nodes that are created with
//! [`CreateMode::Persistent`] are the nodes we have discussed thus far. They remain in the server
//! until you delete them. Nodes that are created with [`CreateMode::Ephemeral`] on the other hand
//! are special. These [ephemeral
//! nodes](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#Ephemeral+Nodes) are
//! automatically deleted by the server when the client that created them disconnects. This can be
//! handy for implementing lease-like mechanisms, and for detecting faults. Since they are
//! automatically deleted, and nodes with children cannot be deleted directly, ephemeral nodes are
//! not allowed to have children.
//!
//! ## Watches
//!
//! In addition to the methods above, [`ZooKeeper::exists`], [`ZooKeeper::get_data`], and
//! [`ZooKeeper::get_children`] also support setting
//! "[watches](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#ch_zkWatches)" on
//! a node. A watch is one-time trigger that causes a [`WatchedEvent`] to be sent to the client
//! that set the watch when the state for which the watch was set changes. For example, for a
//! watched `get_data`, a one-time notification will be sent the first time the data of the target
//! node changes following when the response to the original `get_data` call was processed. You
//! should see the ["Watches" entry in the Programmer's
//! Guide](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#ch_zkWatches) for
//! details.
//!
//! ## Getting started
//!
//! To get ZooKeeper up and running, follow the official [Getting Started
//! Guide](https://zookeeper.apache.org/doc/current/zookeeperStarted.html). In most Linux
//! environments, the procedure for getting a basic setup working is usually just to install the
//! `zookeeper` package and then run `systemctl start zookeeper`. ZooKeeper will then be running at
//! `127.0.0.1:2181`.
//!
//! # This implementation
//!
//! This library is analogous to the asynchronous API offered by the [official Java
//! implementation](https://zookeeper.apache.org/doc/current/api/org/apache/zookeeper/ZooKeeper.html),
//! and for most operations the Java documentation should apply to the Rust implementation. If this
//! is not the case, it is considered [a bug](https://github.com/jonhoo/tokio-zookeeper/issues),
//! and we'd love a bug report with as much relevant information as you can offer.
//!
//! Note that since this implementation is asynchronous, users of the client must take care to
//! not re-order operations in their own code. There is some discussion of this in the [official
//! documentation of the Java
//! bindings](https://zookeeper.apache.org/doc/r3.4.12/zookeeperProgrammers.html#Java+Binding).
//!
//! For more information on ZooKeeper, see the [ZooKeeper Programmer's
//! Guide](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html) and the [Confluence
//! ZooKeeper wiki](https://cwiki.apache.org/confluence/display/ZOOKEEPER/Index). There is also a
//! basic tutorial (that uses the Java client)
//! [here](https://zookeeper.apache.org/doc/current/zookeeperTutorial.html).
//!
//! ## Interaction with Tokio
//!
//! The futures in this crate expect to be running under a `tokio::Runtime`. In the common case,
//! you cannot resolve them solely using `.wait()`, but should instead use `tokio::run` or
//! explicitly create a `tokio::Runtime` and then use `Runtime::block_on`.
//!
//! # A somewhat silly example
//!
//! ```no_run
//! use tokio_zookeeper::*;
//! use futures::prelude::*;
//!
//! # #[tokio::main(flavor = "current_thread")]
//! # async fn main() {
//! let (zk, default_watcher) = ZooKeeper::connect(&"127.0.0.1:2181".parse().unwrap())
//! .await
//! .unwrap();
//!
//! // let's first check if /example exists. the .watch() causes us to be notified
//! // the next time the "exists" status of /example changes after the call.
//! let stat = zk.watch().exists("/example").await.unwrap();
//! // initially, /example does not exist
//! assert_eq!(stat, None);
//! // so let's make it!
//! let path = zk
//! .create(
//! "/example",
//! &b"Hello world"[..],
//! Acl::open_unsafe(),
//! CreateMode::Persistent,
//! )
//! .await
//! .unwrap();
//! assert_eq!(path.as_deref(), Ok("/example"));
//!
//! // does it exist now?
//! let stat = zk.watch().exists("/example").await.unwrap();
//! // looks like it!
//! // note that the creation above also triggered our "exists" watch!
//! assert_eq!(stat.unwrap().data_length as usize, b"Hello world".len());
//!
//! // did the data get set correctly?
//! let res = zk.get_data("/example").await.unwrap();
//! let data = b"Hello world";
//! let res = res.unwrap();
//! assert_eq!(res.0, data);
//! assert_eq!(res.1.data_length as usize, data.len());
//!
//! // let's update the data.
//! let stat = zk
//! .set_data("/example", Some(res.1.version), &b"Bye world"[..])
//! .await
//! .unwrap();
//! assert_eq!(stat.unwrap().data_length as usize, "Bye world".len());
//!
//! // create a child of /example
//! let path = zk
//! .create(
//! "/example/more",
//! &b"Hello more"[..],
//! Acl::open_unsafe(),
//! CreateMode::Persistent,
//! )
//! .await
//! .unwrap();
//! assert_eq!(path.as_deref(), Ok("/example/more"));
//!
//! // it should be visible as a child of /example
//! let children = zk.get_children("/example").await.unwrap();
//! assert_eq!(children, Some(vec!["more".to_string()]));
//!
//! // it is not legal to delete a node that has children directly
//! let res = zk.delete("/example", None).await.unwrap();
//! assert_eq!(res, Err(error::Delete::NotEmpty));
//! // instead we must delete the children first
//! let res = zk.delete("/example/more", None).await.unwrap();
//! assert_eq!(res, Ok(()));
//! let res = zk.delete("/example", None).await.unwrap();
//! assert_eq!(res, Ok(()));
//! // no /example should no longer exist!
//! let stat = zk.exists("/example").await.unwrap();
//! assert_eq!(stat, None);
//!
//! // now let's check that the .watch().exists we did in the very
//! // beginning actually triggered!
//! let (event, _w) = default_watcher.into_future().await;
//! assert_eq!(
//! event,
//! Some(WatchedEvent {
//! event_type: WatchedEventType::NodeCreated,
//! keeper_state: KeeperState::SyncConnected,
//! path: String::from("/example"),
//! })
//! );
//! # }
//! ```
#![deny(missing_docs)]
#![deny(missing_debug_implementations)]
#![deny(missing_copy_implementations)]
use failure::{bail, format_err};
use futures::{channel::oneshot, Stream, TryFutureExt};
use slog::{debug, o, trace};
use std::borrow::Cow;
use std::net::SocketAddr;
use std::time;
/// Per-operation ZooKeeper error types.
pub mod error;
mod proto;
mod transform;
mod types;
use crate::proto::{Watch, ZkError};
pub use crate::types::{
Acl, CreateMode, KeeperState, MultiResponse, Permission, Stat, WatchedEvent, WatchedEventType,
};
/// A connection to ZooKeeper.
///
/// All interactions with ZooKeeper are performed by calling the methods of a `ZooKeeper` instance.
/// All clones of the same `ZooKeeper` instance use the same underlying connection. Once a
/// connection to a server is established, a session ID is assigned to the client. The client will
/// send heart beats to the server periodically to keep the session valid.
///
/// The application can call ZooKeeper APIs through a client as long as the session ID of the
/// client remains valid. If for some reason, the client fails to send heart beats to the server
/// for a prolonged period of time (exceeding the session timeout value, for instance), the server
/// will expire the session, and the session ID will become invalid. The `ZooKeeper` instance will
/// then no longer be usable, and all futures will resolve with a protocol-level error. To make
/// further ZooKeeper API calls, the application must create a new `ZooKeeper` instance.
///
/// If the ZooKeeper server the client currently connects to fails or otherwise does not respond,
/// the client will automatically try to connect to another server before its session ID expires.
/// If successful, the application can continue to use the client.
///
/// Some successful ZooKeeper API calls can leave watches on the "data nodes" in the ZooKeeper
/// server. Other successful ZooKeeper API calls can trigger those watches. Once a watch is
/// triggered, an event will be delivered to the client which left the watch at the first place.
/// Each watch can be triggered only once. Thus, up to one event will be delivered to a client for
/// every watch it leaves.
#[derive(Debug, Clone)]
pub struct ZooKeeper {
#[allow(dead_code)]
connection: proto::Enqueuer,
logger: slog::Logger,
}
/// Builder that allows customizing options for ZooKeeper connections.
#[derive(Debug, Clone)]
pub struct ZooKeeperBuilder {
session_timeout: time::Duration,
logger: slog::Logger,
}
impl Default for ZooKeeperBuilder {
fn default() -> Self {
let drain = slog::Discard;
let root = slog::Logger::root(drain, o!());
ZooKeeperBuilder {
session_timeout: time::Duration::new(0, 0),
logger: root,
}
}
}
impl ZooKeeperBuilder {
/// Connect to a ZooKeeper server instance at the given address.
///
/// A `ZooKeeper` instance is returned, along with a "watcher" that will provide notifications
/// of any changes in state.
///
/// If the connection to the server fails, the client will automatically try to re-connect.
/// Only if re-connection fails is an error returned to the client. Requests that are in-flight
/// during a disconnect may fail and have to be retried.
pub async fn connect(
self,
addr: &SocketAddr,
) -> Result<(ZooKeeper, impl Stream<Item = WatchedEvent>), failure::Error> {
let (tx, rx) = futures::channel::mpsc::unbounded();
tokio::net::TcpStream::connect(addr)
.map_err(failure::Error::from)
.and_then(move |stream| self.handshake(*addr, stream, tx))
.map_ok(move |zk| (zk, rx))
.await
}
/// Set the ZooKeeper [session expiry
/// timeout](https://zookeeper.apache.org/doc/r3.4.12/zookeeperProgrammers.html#ch_zkSessions).
///
/// The default timeout is dictated by the server.
pub fn set_timeout(&mut self, t: time::Duration) {
self.session_timeout = t;
}
/// Set the logger that should be used internally in the ZooKeeper client.
///
/// By default, all logging is disabled. See also [the `slog`
/// documentation](https://docs.rs/slog).
pub fn set_logger(&mut self, l: slog::Logger) {
self.logger = l;
}
async fn handshake(
self,
addr: SocketAddr,
stream: tokio::net::TcpStream,
default_watcher: futures::channel::mpsc::UnboundedSender<WatchedEvent>,
) -> Result<ZooKeeper, failure::Error> {
let request = proto::Request::Connect {
protocol_version: 0,
last_zxid_seen: 0,
timeout: (self.session_timeout.as_secs() * 1_000) as i32
+ self.session_timeout.subsec_millis() as i32,
session_id: 0,
passwd: vec![],
read_only: false,
};
debug!(self.logger, "about to perform handshake");
let plog = self.logger.clone();
let enqueuer = proto::Packetizer::new(addr, stream, plog, default_watcher);
enqueuer.enqueue(request).await.map(move |response| {
trace!(self.logger, "{:?}", response);
ZooKeeper {
connection: enqueuer,
logger: self.logger,
}
})
}
}
impl ZooKeeper {
/// Connect to a ZooKeeper server instance at the given address with default parameters.
///
/// See [`ZooKeeperBuilder::connect`].
pub async fn connect(
addr: &SocketAddr,
) -> Result<(Self, impl Stream<Item = WatchedEvent>), failure::Error> {
ZooKeeperBuilder::default().connect(addr).await
}
/// Create a node with the given `path` with `data` as its contents.
///
/// The `mode` argument specifies additional options for the newly created node.
///
/// If `mode` is set to [`CreateMode::Ephemeral`] (or [`CreateMode::EphemeralSequential`]), the
/// node will be removed by the ZooKeeper automatically when the session associated with the
/// creation of the node expires.
///
/// If `mode` is set to [`CreateMode::PersistentSequential`] or
/// [`CreateMode::EphemeralSequential`], the actual path name of a sequential node will be the
/// given `path` plus a suffix `i` where `i` is the current sequential number of the node. The
/// sequence number is always fixed length of 10 digits, 0 padded. Once such a node is created,
/// the sequential number will be incremented by one. The newly created node's full name is
/// returned when the future is resolved.
///
/// If a node with the same actual path already exists in the ZooKeeper, the returned future
/// resolves with an error of [`error::Create::NodeExists`]. Note that since a different actual
/// path is used for each invocation of creating sequential nodes with the same `path`
/// argument, calls with sequential modes will never return `NodeExists`.
///
/// Ephemeral nodes cannot have children in ZooKeeper. Therefore, if the parent node of the
/// given `path` is ephemeral, the return future resolves to
/// [`error::Create::NoChildrenForEphemerals`].
///
/// If a node is created successfully, the ZooKeeper server will trigger the watches on the
/// `path` left by `exists` calls, and the watches on the parent of the node by `get_children`
/// calls.
///
/// The maximum allowable size of the data array is 1 MB (1,048,576 bytes).
pub async fn create<D, A>(
&self,
path: &str,
data: D,
acl: A,
mode: CreateMode,
) -> Result<Result<String, error::Create>, failure::Error>
where
D: Into<Cow<'static, [u8]>>,
A: Into<Cow<'static, [Acl]>>,
{
let data = data.into();
trace!(self.logger, "create"; "path" => path, "mode" => ?mode, "dlen" => data.len());
self.connection
.enqueue(proto::Request::Create {
path: path.to_string(),
data,
acl: acl.into(),
mode,
})
.await
.and_then(transform::create)
}
/// Set the data for the node at the given `path`.
///
/// The call will succeed if such a node exists, and the given `version` matches the version of
/// the node (if the given `version` is `None`, it matches any version). On success, the
/// updated [`Stat`] of the node is returned.
///
/// This operation, if successful, will trigger all the watches on the node of the given `path`
/// left by `get_data` calls.
///
/// The maximum allowable size of the data array is 1 MB (1,048,576 bytes).
pub async fn set_data<D>(
&self,
path: &str,
version: Option<i32>,
data: D,
) -> Result<Result<Stat, error::SetData>, failure::Error>
where
D: Into<Cow<'static, [u8]>>,
{
let data = data.into();
trace!(self.logger, "set_data"; "path" => path, "version" => ?version, "dlen" => data.len());
let version = version.unwrap_or(-1);
self.connection
.enqueue(proto::Request::SetData {
path: path.to_string(),
version,
data,
})
.await
.and_then(move |r| transform::set_data(version, r))
}
/// Delete the node at the given `path`.
///
/// The call will succeed if such a node exists, and the given `version` matches the node's
/// version (if the given `version` is `None`, it matches any versions).
///
/// This operation, if successful, will trigger all the watches on the node of the given `path`
/// left by `exists` API calls, and the watches on the parent node left by `get_children` API
/// calls.
pub async fn delete(
&self,
path: &str,
version: Option<i32>,
) -> Result<Result<(), error::Delete>, failure::Error> {
trace!(self.logger, "delete"; "path" => path, "version" => ?version);
let version = version.unwrap_or(-1);
self.connection
.enqueue(proto::Request::Delete {
path: path.to_string(),
version,
})
.await
.and_then(move |r| transform::delete(version, r))
}
/// Return the [ACL](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_ZooKeeperAccessControl)
/// and Stat of the node at the given `path`.
///
/// If no node exists for the given path, the returned future resolves with an error of
/// [`error::GetAcl::NoNode`].
pub async fn get_acl(
&self,
path: &str,
) -> Result<Result<(Vec<Acl>, Stat), error::GetAcl>, failure::Error> {
trace!(self.logger, "get_acl"; "path" => path);
self.connection
.enqueue(proto::Request::GetAcl {
path: path.to_string(),
})
.await
.and_then(transform::get_acl)
}
/// Set the [ACL](https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_ZooKeeperAccessControl)
/// for the node of the given `path`.
///
/// The call will succeed if such a node exists and the given `version` matches the ACL version
/// of the node. On success, the updated [`Stat`] of the node is returned.
///
/// If no node exists for the given path, the returned future resolves with an error of
/// [`error::SetAcl::NoNode`]. If the given `version` does not match the ACL version, the
/// returned future resolves with an error of [`error::SetAcl::BadVersion`].
pub async fn set_acl<A>(
&self,
path: &str,
acl: A,
version: Option<i32>,
) -> Result<Result<Stat, error::SetAcl>, failure::Error>
where
A: Into<Cow<'static, [Acl]>>,
{
trace!(self.logger, "set_acl"; "path" => path, "version" => ?version);
let version = version.unwrap_or(-1);
self.connection
.enqueue(proto::Request::SetAcl {
path: path.to_string(),
acl: acl.into(),
version,
})
.await
.and_then(move |r| transform::set_acl(version, r))
}
}
impl ZooKeeper {
/// Add a global watch for the next chained operation.
pub fn watch(&self) -> WatchGlobally {
WatchGlobally(self)
}
/// Add a watch for the next chained operation, and return a future for any received event
/// along with the operation's (successful) result.
pub fn with_watcher(&self) -> WithWatcher {
WithWatcher(self)
}
async fn exists_w(&self, path: &str, watch: Watch) -> Result<Option<Stat>, failure::Error> {
trace!(self.logger, "exists"; "path" => path, "watch" => ?watch);
self.connection
.enqueue(proto::Request::Exists {
path: path.to_string(),
watch,
})
.await
.and_then(transform::exists)
}
/// Return the [`Stat`] of the node of the given `path`, or `None` if the node does not exist.
pub async fn exists(&self, path: &str) -> Result<Option<Stat>, failure::Error> {
self.exists_w(path, Watch::None).await
}
async fn get_children_w(
&self,
path: &str,
watch: Watch,
) -> Result<Option<Vec<String>>, failure::Error> {
trace!(self.logger, "get_children"; "path" => path, "watch" => ?watch);
self.connection
.enqueue(proto::Request::GetChildren {
path: path.to_string(),
watch,
})
.await
.and_then(transform::get_children)
}
/// Return the names of the children of the node at the given `path`, or `None` if the node
/// does not exist.
///
/// The returned list of children is not sorted and no guarantee is provided as to its natural
/// or lexical order.
pub async fn get_children(&self, path: &str) -> Result<Option<Vec<String>>, failure::Error> {
self.get_children_w(path, Watch::None).await
}
async fn get_data_w(
&self,
path: &str,
watch: Watch,
) -> Result<Option<(Vec<u8>, Stat)>, failure::Error> {
trace!(self.logger, "get_data"; "path" => path, "watch" => ?watch);
self.connection
.enqueue(proto::Request::GetData {
path: path.to_string(),
watch,
})
.await
.and_then(transform::get_data)
}
/// Return the data and the [`Stat`] of the node at the given `path`, or `None` if it does not
/// exist.
pub async fn get_data(&self, path: &str) -> Result<Option<(Vec<u8>, Stat)>, failure::Error> {
self.get_data_w(path, Watch::None).await
}
/// Start building a multi request. Multi requests batch several operations
/// into one atomic unit.
pub fn multi(&self) -> MultiBuilder {
MultiBuilder {
zk: self,
requests: Vec::new(),
}
}
}
/// Proxy for [`ZooKeeper`] that adds watches for initiated operations.
///
/// Triggered watches produce events on the global watcher stream.
#[derive(Debug, Clone)]
pub struct WatchGlobally<'a>(&'a ZooKeeper);
impl<'a> WatchGlobally<'a> {
/// Return the [`Stat`] of the node of the given `path`, or `None` if the node does not exist.
///
/// If no errors occur, a watch is left on the node at the given `path`. The watch is triggered
/// by any successful operation that creates or deletes the node, or sets the node's data. When
/// the watch triggers, an event is sent to the global watcher stream.
pub async fn exists(&self, path: &str) -> Result<Option<Stat>, failure::Error> {
self.0.exists_w(path, Watch::Global).await
}
/// Return the names of the children of the node at the given `path`, or `None` if the node
/// does not exist.
///
/// The returned list of children is not sorted and no guarantee is provided as to its natural
/// or lexical order.
///
/// If no errors occur, a watch is left on the node at the given `path`. The watch is triggered
/// by any successful operation that deletes the node at the given `path`, or creates or
/// deletes a child of that node. When the watch triggers, an event is sent to the global
/// watcher stream.
pub async fn get_children(&self, path: &str) -> Result<Option<Vec<String>>, failure::Error> {
self.0.get_children_w(path, Watch::Global).await
}
/// Return the data and the [`Stat`] of the node at the given `path`, or `None` if it does not
/// exist.
///
/// If no errors occur, a watch is left on the node at the given `path`. The watch is triggered
/// by any successful operation that sets the node's data, or deletes it. When the watch
/// triggers, an event is sent to the global watcher stream.
pub async fn get_data(&self, path: &str) -> Result<Option<(Vec<u8>, Stat)>, failure::Error> {
self.0.get_data_w(path, Watch::Global).await
}
}
/// Proxy for [`ZooKeeper`] that adds non-global watches for initiated operations.
///
/// Events from triggered watches are yielded through returned `oneshot` channels. All events are
/// also produced on the global watcher stream.
#[derive(Debug, Clone)]
pub struct WithWatcher<'a>(&'a ZooKeeper);
impl<'a> WithWatcher<'a> {
/// Return the [`Stat`] of the node of the given `path`, or `None` if the node does not exist.
///
/// If no errors occur, a watch will be left on the node at the given `path`. The watch is
/// triggered by any successful operation that creates or deletes the node, or sets the data on
/// the node, and in turn causes the included `oneshot::Receiver` to resolve.
pub async fn exists(
&self,
path: &str,
) -> Result<(oneshot::Receiver<WatchedEvent>, Option<Stat>), failure::Error> {
let (tx, rx) = oneshot::channel();
self.0
.exists_w(path, Watch::Custom(tx))
.await
.map(|r| (rx, r))
}
/// Return the names of the children of the node at the given `path`, or `None` if the node
/// does not exist.
///
/// The returned list of children is not sorted and no guarantee is provided as to its natural
/// or lexical order.
///
/// If no errors occur, a watch is left on the node at the given `path`. The watch is triggered
/// by any successful operation that deletes the node at the given `path`, or creates or
/// deletes a child of that node, and in turn causes the included `oneshot::Receiver` to
/// resolve.
pub async fn get_children(
&self,
path: &str,
) -> Result<Option<(oneshot::Receiver<WatchedEvent>, Vec<String>)>, failure::Error> {
let (tx, rx) = oneshot::channel();
self.0
.get_children_w(path, Watch::Custom(tx))
.await
.map(|r| (r.map(move |c| (rx, c))))
}
/// Return the data and the [`Stat`] of the node at the given `path`, or `None` if it does not
/// exist.
///
/// If no errors occur, a watch is left on the node at the given `path`. The watch is triggered
/// by any successful operation that sets the node's data, or deletes it, and in turn causes
/// the included `oneshot::Receiver` to resolve.
pub async fn get_data(
&self,
path: &str,
) -> Result<Option<(oneshot::Receiver<WatchedEvent>, Vec<u8>, Stat)>, failure::Error> {
let (tx, rx) = oneshot::channel();
self.0
.get_data_w(path, Watch::Custom(tx))
.await
.map(|r| (r.map(move |(b, s)| (rx, b, s))))
}
}
/// Proxy for [`ZooKeeper`] that batches operations into an atomic "multi" request.
#[derive(Debug)]
pub struct MultiBuilder<'a> {
zk: &'a ZooKeeper,
requests: Vec<proto::Request>,
}
impl<'a> MultiBuilder<'a> {
/// Attach a create operation to this multi request.
///
/// See [`ZooKeeper::create`] for details.
pub fn create<D, A>(mut self, path: &str, data: D, acl: A, mode: CreateMode) -> Self
where
D: Into<Cow<'static, [u8]>>,
A: Into<Cow<'static, [Acl]>>,
{
self.requests.push(proto::Request::Create {
path: path.to_string(),
data: data.into(),
acl: acl.into(),
mode,
});
self
}
/// Attach a set data operation to this multi request.
///
/// See [`ZooKeeper::set_data`] for details.
pub fn set_data<D>(mut self, path: &str, version: Option<i32>, data: D) -> Self
where
D: Into<Cow<'static, [u8]>>,
{
self.requests.push(proto::Request::SetData {
path: path.to_string(),
version: version.unwrap_or(-1),
data: data.into(),
});
self
}
/// Attach a delete operation to this multi request.
///
/// See [`ZooKeeper::delete`] for details.
pub fn delete(mut self, path: &str, version: Option<i32>) -> Self {
self.requests.push(proto::Request::Delete {
path: path.to_string(),
version: version.unwrap_or(-1),
});
self
}
/// Attach a check operation to this multi request.
///
/// There is no equivalent to the check operation outside of a multi
/// request.
pub fn check(mut self, path: &str, version: i32) -> Self {
self.requests.push(proto::Request::Check {
path: path.to_string(),
version,
});
self
}
/// Run executes the attached requests in one atomic unit.
pub async fn run(self) -> Result<Vec<Result<MultiResponse, error::Multi>>, failure::Error> {
let (zk, requests) = (self.zk, self.requests);
let reqs_lite: Vec<transform::RequestMarker> = requests.iter().map(|r| r.into()).collect();
zk.connection
.enqueue(proto::Request::Multi(requests))
.await
.and_then(move |r| match r {
Ok(proto::Response::Multi(responses)) => reqs_lite
.iter()
.zip(responses)
.map(|(req, res)| transform::multi(req, res))
.collect(),
Ok(r) => bail!("got non-multi response to multi: {:?}", r),
Err(e) => Err(format_err!("multi call failed: {:?}", e)),
})
}
}
#[cfg(test)]
mod tests {
use super::*;
use futures::StreamExt;
use slog::Drain;
#[tokio::test]
async fn it_works() {
let mut builder = ZooKeeperBuilder::default();
let decorator = slog_term::TermDecorator::new().build();
let drain = slog_term::FullFormat::new(decorator).build().fuse();
let drain = slog_async::Async::new(drain).build().fuse();
builder.set_logger(slog::Logger::root(drain, o!()));
let (zk, w) = builder
.connect(&"127.0.0.1:2181".parse().unwrap())
.await
.unwrap();
let (exists_w, stat) = zk.with_watcher().exists("/foo").await.unwrap();
assert_eq!(stat, None);
let stat = zk.watch().exists("/foo").await.unwrap();
assert_eq!(stat, None);
let path = zk
.create(
"/foo",
&b"Hello world"[..],
Acl::open_unsafe(),
CreateMode::Persistent,
)
.await
.unwrap();
assert_eq!(path.as_ref().map(String::as_str), Ok("/foo"));
let event = exists_w
.map_err(|e| format_err!("exists_w failed: {:?}", e))
.await
.unwrap();
assert_eq!(
event,
WatchedEvent {
event_type: WatchedEventType::NodeCreated,
keeper_state: KeeperState::SyncConnected,
path: String::from("/foo"),
}
);
let stat = zk.watch().exists("/foo").await.unwrap();
assert_eq!(stat.unwrap().data_length as usize, b"Hello world".len());
let res = zk.get_acl("/foo").await.unwrap();
let (acl, _) = res.unwrap();
assert_eq!(acl, Acl::open_unsafe());
let res = zk.get_data("/foo").await.unwrap();
let data = b"Hello world";
let res = res.unwrap();
assert_eq!(res.0, data);
assert_eq!(res.1.data_length as usize, data.len());
let stat = zk
.set_data("/foo", Some(res.1.version), &b"Bye world"[..])
.await
.unwrap();
assert_eq!(stat.unwrap().data_length as usize, "Bye world".len());
let res = zk.get_data("/foo").await.unwrap();
let data = b"Bye world";
let res = res.unwrap();
assert_eq!(res.0, data);
assert_eq!(res.1.data_length as usize, data.len());
let path = zk
.create(
"/foo/bar",
&b"Hello bar"[..],
Acl::open_unsafe(),
CreateMode::Persistent,
)
.await
.unwrap();
assert_eq!(path.as_deref(), Ok("/foo/bar"));
let children = zk.get_children("/foo").await.unwrap();
assert_eq!(children, Some(vec!["bar".to_string()]));
let res = zk.get_data("/foo/bar").await.unwrap();
let data = b"Hello bar";
let res = res.unwrap();
assert_eq!(res.0, data);
assert_eq!(res.1.data_length as usize, data.len());
// add a new exists watch so we'll get notified of delete
let _ = zk.watch().exists("/foo").await.unwrap();
let res = zk.delete("/foo", None).await.unwrap();
assert_eq!(res, Err(error::Delete::NotEmpty));
let res = zk.delete("/foo/bar", None).await.unwrap();
assert_eq!(res, Ok(()));
let res = zk.delete("/foo", None).await.unwrap();
assert_eq!(res, Ok(()));
let stat = zk.watch().exists("/foo").await.unwrap();
assert_eq!(stat, None);
let (event, w) = w.into_future().await;
assert_eq!(
event,
Some(WatchedEvent {
event_type: WatchedEventType::NodeCreated,
keeper_state: KeeperState::SyncConnected,
path: String::from("/foo"),
})
);
let (event, w) = w.into_future().await;
assert_eq!(
event,
Some(WatchedEvent {
event_type: WatchedEventType::NodeDataChanged,
keeper_state: KeeperState::SyncConnected,
path: String::from("/foo"),
})
);
let (event, w) = w.into_future().await;
assert_eq!(
event,
Some(WatchedEvent {
event_type: WatchedEventType::NodeDeleted,
keeper_state: KeeperState::SyncConnected,
path: String::from("/foo"),
})
);
drop(zk); // make Packetizer idle
assert_eq!(w.count().await, 0);
}
#[tokio::test]
async fn example() {
let (zk, default_watcher) = ZooKeeper::connect(&"127.0.0.1:2181".parse().unwrap())
.await
.unwrap();
// let's first check if /example exists. the .watch() causes us to be notified
// the next time the "exists" status of /example changes after the call.
let stat = zk.watch().exists("/example").await.unwrap();
// initially, /example does not exist
assert_eq!(stat, None);
// so let's make it!
let path = zk
.create(
"/example",
&b"Hello world"[..],
Acl::open_unsafe(),
CreateMode::Persistent,
)
.await
.unwrap();
assert_eq!(path.as_deref(), Ok("/example"));
// does it exist now?
let stat = zk.watch().exists("/example").await.unwrap();
// looks like it!
// note that the creation above also triggered our "exists" watch!
assert_eq!(stat.unwrap().data_length as usize, b"Hello world".len());
// did the data get set correctly?
let res = zk.get_data("/example").await.unwrap();
let data = b"Hello world";
let res = res.unwrap();
assert_eq!(res.0, data);
assert_eq!(res.1.data_length as usize, data.len());
// let's update the data.
let stat = zk
.set_data("/example", Some(res.1.version), &b"Bye world"[..])
.await
.unwrap();
assert_eq!(stat.unwrap().data_length as usize, "Bye world".len());
// create a child of /example
let path = zk
.create(
"/example/more",
&b"Hello more"[..],
Acl::open_unsafe(),
CreateMode::Persistent,
)
.await
.unwrap();
assert_eq!(path.as_deref(), Ok("/example/more"));
// it should be visible as a child of /example
let children = zk.get_children("/example").await.unwrap();
assert_eq!(children, Some(vec!["more".to_string()]));
// it is not legal to delete a node that has children directly
let res = zk.delete("/example", None).await.unwrap();
assert_eq!(res, Err(error::Delete::NotEmpty));
// instead we must delete the children first
let res = zk.delete("/example/more", None).await.unwrap();
assert_eq!(res, Ok(()));
let res = zk.delete("/example", None).await.unwrap();
assert_eq!(res, Ok(()));
// no /example should no longer exist!
let stat = zk.exists("/example").await.unwrap();
assert_eq!(stat, None);
// now let's check that the .watch().exists we did in the very
// beginning actually triggered!
let (event, _w) = default_watcher.into_future().await;
assert_eq!(
event,
Some(WatchedEvent {
event_type: WatchedEventType::NodeCreated,
keeper_state: KeeperState::SyncConnected,
path: String::from("/example"),
})
);
}
#[tokio::test]
async fn acl_test() {
let mut builder = ZooKeeperBuilder::default();
let decorator = slog_term::TermDecorator::new().build();
let drain = slog_term::FullFormat::new(decorator).build().fuse();
let drain = slog_async::Async::new(drain).build().fuse();
builder.set_logger(slog::Logger::root(drain, o!()));
let (zk, _) = (builder.connect(&"127.0.0.1:2181".parse().unwrap()))
.await
.unwrap();
let _ = zk
.create(
"/acl_test",
&b"foo"[..],
Acl::open_unsafe(),
CreateMode::Ephemeral,
)
.await
.unwrap();
let res = zk.get_acl("/acl_test").await.unwrap();
let res = res.unwrap();
assert_eq!(res.0, Acl::open_unsafe());
let res = zk
.set_acl("/acl_test", Acl::creator_all(), Some(res.1.version))
.await
.unwrap();
// a not authenticated user is not able to set `auth` scheme acls.
assert_eq!(res, Err(error::SetAcl::InvalidAcl));
let stat = zk
.set_acl("/acl_test", Acl::read_unsafe(), None)
.await
.unwrap();
// successfully change node acl to `read_unsafe`
assert_eq!(stat.unwrap().data_length as usize, b"foo".len());
let res = zk.get_acl("/acl_test").await.unwrap();
let res = res.unwrap();
assert_eq!(res.0, Acl::read_unsafe());
let res = zk.set_data("/acl_test", None, &b"bar"[..]).await.unwrap();
// cannot set data on a read only node
assert_eq!(res, Err(error::SetData::NoAuth));
let res = zk
.set_acl("/acl_test", Acl::open_unsafe(), None)
.await
.unwrap();
// cannot change a read only node's acl
assert_eq!(res, Err(error::SetAcl::NoAuth));
drop(zk); // make Packetizer idle
}
#[tokio::test]
async fn multi_test() {
let mut builder = ZooKeeperBuilder::default();
let decorator = slog_term::TermDecorator::new().build();
let drain = slog_term::FullFormat::new(decorator).build().fuse();
let drain = slog_async::Async::new(drain).build().fuse();
builder.set_logger(slog::Logger::root(drain, o!()));
async fn check_exists(zk: &ZooKeeper, paths: &[&str]) -> Result<Vec<bool>, failure::Error> {
let mut res = Vec::new();
for p in paths {
let exists = zk.exists(p).await?;
res.push(exists.is_some());
}
Result::<_, failure::Error>::Ok(res)
}
let (zk, _) = builder
.connect(&"127.0.0.1:2181".parse().unwrap())
.await
.unwrap();
let res = zk
.multi()
.create("/b", &b"a"[..], Acl::open_unsafe(), CreateMode::Persistent)
.create("/c", &b"b"[..], Acl::open_unsafe(), CreateMode::Persistent)
.run()
.await
.unwrap();
assert_eq!(
res,
[
Ok(MultiResponse::Create("/b".into())),
Ok(MultiResponse::Create("/c".into()))
]
);
let res = check_exists(&zk, &["/a", "/b", "/c", "/d"]).await.unwrap();
assert_eq!(res, &[false, true, true, false]);
let res = zk
.multi()
.create("/a", &b"a"[..], Acl::open_unsafe(), CreateMode::Persistent)
.create("/b", &b"b"[..], Acl::open_unsafe(), CreateMode::Persistent)
.create("/c", &b"b"[..], Acl::open_unsafe(), CreateMode::Persistent)
.create("/d", &b"a"[..], Acl::open_unsafe(), CreateMode::Persistent)
.run()
.await
.unwrap();
assert_eq!(
res,
&[
Err(error::Multi::RolledBack),
Err(error::Multi::Create(error::Create::NodeExists)),
Err(error::Multi::Skipped),
Err(error::Multi::Skipped),
]
);
let res = check_exists(&zk, &["/a", "/b", "/c", "/d"]).await.unwrap();
assert_eq!(res, &[false, true, true, false]);
let res = zk
.multi()
.set_data("/b", None, &b"garbaggio"[..])
.run()
.await
.unwrap();
match res[0] {
Ok(MultiResponse::SetData(stat)) => {
assert_eq!(stat.data_length as usize, "garbaggio".len())
}
_ => panic!("unexpected response: {res:?}"),
}
let res = zk
.multi()
.check("/b", 0)
.delete("/c", None)
.run()
.await
.unwrap();
assert_eq!(
res,
[
Err(error::Multi::Check(error::Check::BadVersion {
expected: 0
})),
Err(error::Multi::Skipped),
]
);
let res = check_exists(&zk, &["/a", "/b", "/c", "/d"]).await.unwrap();
assert_eq!(res, &[false, true, true, false]);
let res = zk.multi().check("/a", 0).run().await.unwrap();
assert_eq!(res, &[Err(error::Multi::Check(error::Check::NoNode)),]);
let res = zk
.multi()
.check("/b", 1)
.delete("/b", None)
.check("/c", 0)
.delete("/c", None)
.run()
.await
.unwrap();
assert_eq!(
res,
[
Ok(MultiResponse::Check),
Ok(MultiResponse::Delete),
Ok(MultiResponse::Check),
Ok(MultiResponse::Delete),
]
);
let res = check_exists(&zk, &["/a", "/b", "/c", "/d"]).await.unwrap();
assert_eq!(res, [false, false, false, false]);
drop(zk); // make Packetizer idle
}
}